Certain nicotine-dependent smokers smoke in order to modify or suppress unpleasant states such as negative affect and nicotine withdrawal. For these smokers, the immediate avoidance of troublesome thoughts, feelings, or sensations appears to take precedence over the known health risks associated with smoking. This proposal suggests a treatment model for nicotine-dependent smokers derived from the experimental literature on suppression, acceptance, and social support. This biobehavioral model is applied to the hypothesized mechanism of action in slow release bupropion, a promising new treatment for smoking cessation. A psychosocial component using social support to facilitate acceptance skills training for nicotine-dependent smokers is proposed. It is hypothesized that acceptance, suppression, and in-session social support may mediate treatment effects and moderate the impact of withdrawal symptoms and negative affect on treatment outcome. The specific aims are (a) to use the Experiential Acceptance and Support model to generate a manual integrating relevant interventions from Acceptance and Commitment Therapy and Functional Analytic Psychotherapy, to be used as a psychosocial component in the treatment of nicotine-dependent smokers, (b) to investigate theory-specified variables that may reflect on the putative mechanisms underlying the proposed treatment and slow release bupropion, (c) to pilot the combined treatment, (d) to evaluate the role of withdrawal symptoms and negative affect on treatment process and outcome, (d) to evaluate the clinical acceptability of the proposed treatment, and (e) to generate data to use in a power analysis for future studies.